This is an incredible time to be an astronomer. Actually, it’s an incredible time for anybodywho is interested in our place in the universe. The last few decades have seen the advent of technologies that have allowed us to see further into space than ever before.

One of the advantages of looking further away is that in astronomy, this also means looking further back in time. Light travels extremely quickly from point to point, but the distances between celestial objects are so vast that the time their light takes to reach us is significant. Start close to home, with the Sun, for example. Its light takes eight minutes to reach us here on Earth. Spacecraft operating in the distant reaches of the outer solar system – like NASA’s Cassini probe, currently exploring Saturn and its amazing family of moons – must be autonomous, because signals from Earth can take more than an hour to reach them. The nearest star is four light years away, and so we see it as it was in 2003. The center of the Milky Way is 25,000 light years away, and the nearest large galaxy, Andromeda, is 2.2 million light years away, and this immense distance takes us no further than our local neighbourhood.

Instruments like the Very Large Telescope at the Paranal Observatory in Chile have been responsible for many cosmic discoveries. (Photo: European Southern Observatory)

Looking back in time in this way, we see a universe that looks different from the one around us. Galaxies, for example, tend to look smaller than they are now, because when the light we see left them, they were still in the process of assembling. Star formation was more rapid back then; the universe of today is, perhaps depressingly, past its peak, and the rate at which new stars are being born is declining. This evolving universe provides the most straightforward evidence that there really is a cosmic story, with a beginning many billions of years ago.

In fact, analysis of this early universe, together with a lot of work and many other observations besides, has allowed us to conclude that our universe began in an almost unimaginably hot, dense state some 13.7 billion years ago. The sophistication of modern cosmological measurements can be breathtaking; we know the age of the universe more accurately than we know the age of the Earth. We also know what the major constituents of the universe are, but this raises more questions. Ordinary matter, made of atoms of carbon, oxygen, nitrogen and all the rest, turns out to account for only a sixth of the mass in the universe, the rest being a mysterious substance which we call ”dark matter.” The expansion of the universe is not, as once was expected, slowing down under the pull of gravity, but rather accelerating under the influence of an antigravity force that remained undetected until just 10 years ago.

We have made progress in other areas too. The search for life beyond our own planet, and beyond our own solar system, is something that has inspired scientists, artists and authors for centuries. There is still no sign of little green men, bug-eyed monsters or bacteria on Mars, but we are getting somewhere. The detection of planets beyond our solar system is now routine; more than 200 of these extra-solar planets, or exoplanets, are now known. All are large – probably because large planets are easy to detect – but it would not be surprising if the first Earth-sized worlds known to orbit another star were detected in the next year or two. The first measurement of the composition of the atmosphere of two of these planets was announced just a few weeks ago, and the pace of discovery is rapid.

With so much going on – we haven’t mentioned the exploration of Mars, or the grandstand view we have of merging galaxies and much, much else – it is difficult to know where to look next. In this column, we hope to show you around our universe. After all, the story belongs to all of us, insignificant though our place in it must be.

I have two questions that I hope you will collectively answer during the course of your writings:

1). If the universe is 13.7 billion years old and the Milky Way is in no particular part of it (ie we don’t know that the universe has a center), how is it that we can detect signals from 12 or so billion years from every direction. If the universe has been expanding from a singlarity, doesn’t that mean that something is close to an edge and should be seeing more signals from one direction than the other.

2). If there is so much dark matter around, why isn’t there any near us? Or is it that we haven’t learned how to detect it?

i’m glad that we now have an astronomy blog. that the universe is for the most part, so mind-numbingly empty and vast cannot be overstated.

whilst we can readily detect other planets around other star systems, most of these are huge gas giants, much like jupiter in our own solar system. perhaps our author can explain just how far out one has to travel away from the earth for our own planet to be completely undetectable.

a dose of reality never hurt anyone’s perspective, i’m also an amateur astronomer.

I really look forward to more. And like John have a question I hope you will address. Given that the universe is 13.7 billion years old, how long is it forecast to last before entropy does it in? Or is that still the expectation?

As a dedicated amateur astronomer, I am delighted to have this blog to check in on from time to time. I feel we are close to some amazing discoveries, perhaps even to finding some evidence of extra-terrestrial life. Maybe the coming Democratic administration won’t be so anti-science or such narrow-minded bozos as the present ship of fools. But hurry. I am 67 and counting.

It’s so exciting to be alive in the twenty first century and to have (thanks to science and technology), a front row seat at the greatest show on earth a/k/a, the ever expanding universe. The truth is out there let’s keep looking.

In reverse order, there is expected to be dark matter in our neighborhood, but it is only inferred from its effect, through gravity, on observable matter. Its presence is supposed to explain why the outer reaches of the Milky Way can orbit faster than expected. There is a project hoping to spot clumps within the Milky Way, through local gravity effects.

While the math of general relativity provides models that are self-consistent for self-contained spaces they’re not readily intuitive.

The idea of a space without an edge is a tough one, and I’ve never really found an image that works. But we usually hear that space comes into existence along with matter; matter did not expand into space (there was no “center”, since even with a singularity there was no outside).

It’s perhaps easier to accept that we are not able to see as far as the age would allow, given light speed, and with enough expansion the horizon would recede too far anyway. So even if there were a center we would see the same distance in all directions. And even if light paths curved around, as they would in a positively curved space, we can’t see far enough to notice the effect. Observation could show indirect clues, but nothing conclusive has been found yet. There are some vague hints from the microwave background.

And between two possibilities, that of enough expansion energy to keep going, and that that will reverse eventually, the former seems the best fit to the evidence. Although it’s a poor analogy, it is pretty much like escape velocity. In this case space is escaping from itself, not one hunk of matter escaping from the local gravity of another.

Good introductory essay. You might have mentioned that Andromeda is coming our way, for a visit, sometime in the next billion years, or less. Also, for one of your next essays, you ought to talk about black holes. And it might be exciting to your readers to discuss the spinning black hole in the central galaxy of the Perseus Cluster.

Excellent to have this subject to kick around again. Some years ago we had the Times’ bulletin board, and the discussin on cosmology got quite interesting. I hope this blog picks up the thread again.

After bumping up against branes, multiple universes and all that, as I recall, the participants came to the reluctant conclusion that nobody really know anything about anything when it comes to prime beginnings. However, that was several years ago…

Is there any way to explain what is conceived of as ‘being’ pre the big bang?
Is it possible we are still actively in the bang, rather thanseeing a passively (anti-gravity?) expanding post bang universe?

If there is anything that could literally “save” the human race and this magnificent planet it is coming to know the universe story. That the elements we are composed of are forged only in a dying star so that we are truly stardust. And to understand that in the story of evolution humans are the universe looking back on itself — and so much more. Could there be a more riveting origin story to tell our children!

Looking out from our small blue dot I find quasars fascinating. We can only see them because they are hugely bright. They cannot see us at all. They are billions of light years away, that means we are seeing them as and where they were billions of years ago. Where are they and what are they doing now?

This is probably an incredibly stupid thing to say, as I am more or less a cosmological ignormamus, but wouldn’t it be possible that the “dark matter” inferred by gravitational force effect and the “antigravitational force” impelling acceleration of universal expansion, be one and the same? To be so (and to be coming from every direction at once as both of these effects would require, would imply that gravitational (or similar) force might be transdimensional. If gravitation could exert effects across dimensions, there could be forces enacted on our visible dimensional universe seemingly from all directions at once, that could be uneven (due to morphological anomalies in a non visible other dimension)and could also exert the “progravitational” forces imputed to dark matter. Just a thought.

We know so much about the universe yet so little about the Earth we inhabit. We have only penetrated about five miles into the Earth’s core and know little about the thermal energy generated there. Only since the advent of sattelites have we been able to accurately track and photograph ocean currents and their relation to our climate and weather. Yet we panic when Al Gore makes a trumped up movie about global warming.
Nature never works in straight lines. We have, and will continue to have global warming and cooling as we have had over the eons.

Can only echo first comment, and add that ever since I first read one of Patrick Moore’s beautiful early books almost 50 years ago, I have always loved his work and I’m delighted to see him appear along with May and Lintott!! I eagerly anticipate each and every forthcoming appearance. The Postings were also most enjoyable, especially the tidbits from those more steeped in knowledge. Many thanks to one and all, and to the New York Times!!!!

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About

Sir Patrick Moore has been the host of “The Sky at Night,” a monthly television show about astronomy on the BBC, for 50 years. He is the author of more than 60 books on astronomy, and his own studies have focused on the Moon. Moore is also an accomplished xylophone player and composer. He is a coauthor, with Chris Lintott and Brian May, of “Bang!: The Complete History of the Universe,” which will be published in the United States this fall.

Brian May, best known as a guitarist, songwriter and performer for Queen, began his doctoral studies on the subject of interplanetary dust before the band hit it big in the early 1970s. Through the years, he retained a strong interest in astronomy, appearing regularly on Moore’s TV show, “The Sky at Night.” May has recently returned to his studies in astrophysics. He is a coauthor of “Bang!”

Chris Lintott, has been a co-host (with Sir Patrick Moore) of “The Sky at Night” since 2000. He recently completed his doctorate and is now studying star formation at the University of Oxford. He is a coauthor of “Bang!”